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A Comparison Study of the Ridge Filter Parameter by Using FLUKA and GEANT4 Simulation Codes
Yongkeun Song,Jaeik Shin,Sungho Cho,Seunghoon Yoo,Ilsung Cho,Eunho Kim,Wongyun Jung,Sanghyoun Choi,오경민 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.1
We investigated the parameter optimization of the ridge filter’s thickness for carbon-ion therapy by using a Monte Carlo simulation. For this study, a ridge filter was designed for the spreadout Bragg peak (SOBP) by considering the relative biological effectiveness (RBE). The thickness, height, and width of the ridge filter were designed by using the FLUKA and the GEANT4 codes, and we analyzed and compared the results of the physical dose distributions for the FLUKA and the GEANT4 codes. The results showed that the minimum width of the groove for the ridge filter should be at least 0.5 cm for an appropriate biological dose. The SOBP sections were 8 cm, 9 cm, and 10 cm, respectively, when the heights were 3.5 cm, 4.0 cm, and 4.5 cm. The height of the ridge filter was designed to be associated with the SOBP width. Also, the results for the FLUKA and the GEANT4 codes showed that the average value of the difference was 3% and that the maximum error was 5%; however, the trends were similar. Therefore, the height and the width of the groove for the ridge filter are important parameters for deciding the length and the plateau of the SOBP.
Polymerization of 3TUTS SAM Formed on ITO Substrates
Choi, Sung Jin,Son, Yongkeun,Lee, Youngkwan,Kim, Kyo-Hyeok,Chung, Il-Sub TaylorFrancis 2007 Molecular Crystals and Liquid Crystals Vol.471 No.1
<P> Surface modification of ITO with polythiophene derivative, poly(3-TUTS), was done for molecular electronic device application purpose. In order to prepare a derivative of polythiophene having n-alkyltrichlorosilane at 3-position of the thiophene ring, the monomer of thienyl-functionalized n-alkyltrichlorosilane, 11-(3-thienyl)undecyltrichlorosilane (3TUTS), was synthesized. The monomer was identified by using NMR, UV/VIS spectroscopic methods. Surfaces of ITO substrates were modified with the synthesized 3TUTS to get SAM on them. Polymerization of the SAM was done by dipping this SAM into FeCl3 solution. The polymer have been identified by using Cyclic Voltammetry, UV/VIS spectroscopy, scanning electron microscopy (SEM), DFM (Dynamic Force Microscopy) image analysis.</P>
Choi Hyohun,Lee Jang Hoon,Park Hyuk Kyoon,Lee Eunkyu,Kim Myeong Seop,Kim Hyeon Jeong,Park Bo Eun,Kim Hong Nyun,Kim Namkyun,Jang Se Yong,Bae Myung Hwan,Yang Dong Heon,Park Hun Sik,Cho Yongkeun 대한의학회 2022 Journal of Korean medical science Vol.37 No.21
Background: It has been known that the fear of contagion during the coronavirus disease 2019 (COVID-19) creates time delays with subsequent impact on mortality in patients with acute myocardial infarction (AMI). However, difference of time delay and clinical outcome in patients with ST-segment elevation myocardial infarction (STEMI) or non-STEMI between the COVID-19 pandemic and pre-pandemic era has not been fully investigated yet in Korea. The aim of this study was to investigate the impact of COVID-19 pandemic on time delays and clinical outcome in patients with STEMI or non-STEMI compared to the same period years prior. Methods: A total of 598 patients with STEMI (n = 195) or non-STEMI (n = 403) who underwent coronary angiography during the COVID-19 pandemic (February 1 to April 30, 2020) and prepandemic era (February 1 to April 30, 2017, 2018, and 2019) were analyzed in this study. Main outcomes were the incidence of time delay, cardiac arrest, and in-hospital death. Results: There was 13.5% reduction in the number of patients hospitalized with AMI during the pandemic compared to pre-pandemic era. In patients with STEMI, door to balloon time tended to be longer during the pandemic compared to pre-pandemic era (55.7 ± 12.6 minutes vs. 60.8 ± 13.0 minutes, P = 0.08). There were no significant differences in cardiac arrest (15.6% vs. 10.4%, P = 0.397) and in-hospital mortality (15.6% vs. 10.4%, P = 0.397) between pre-pandemic and the pandemic era. In patients with non-STEMI, symptom to door time was significantly longer (310.0 ± 346.2 minutes vs. 511.5 ± 635.7 minutes, P = 0.038) and the incidence of cardiac arrest (0.9% vs. 3.5%, P = 0.017) and in-hospital mortality (0.3% vs. 2.3%, P = 0.045) was significantly greater during the pandemic compared to pre-pandemic era. Among medications, angiotensin converting enzyme inhibitors/angiotensin type 2 receptor blockers (ACE-I/ARBs) were underused in STEMI (64.6% vs. 45.8%, P = 0.021) and non-STEMI (67.8% vs. 57.0%, P = 0.061) during the pandemic. Conclusion: During the COVID-19 pandemic, there has been a considerable reduction in hospital admissions for AMI, time delay, and underuse of ACE-I/ARBs for the management of AMI, and this might be closely associated with the excess death in Korea.
Yongkeun Song,Seunguk Heo,Gyuseok Cho,Sanghyun Choi,Moojae Han,Jikoon Park 한국방사선학회 2017 한국방사선학회 논문지 Vol.11 No.6
꿈의 암치료기라고 불리는 중입자 치료는 환자의 암세포에 입사하여 암세포만을 사멸하고 사라지는데 이때 중성자 및 감마선이 발생되어 치료실 내 영상장비, 그 밖의 전자장비에 영향을 미치게 된다. 중입자 치료시설을 구축하기 위해서는 약 2,000억 원 가량의 예산이 필요하며 구축기간도 5년 이상 소요된다. 따 라서 구축 전 몬테카를로 시뮬레이션을 이용하여 치료실 내 선량 분포에 대해 관찰하여 적절한 대비를 하 는 것이 중요하다. 본 연구에서는 몬테카를로 시뮬레이션 툴인 FLUKA를 이용하여 중입자 치료 시 치료실 내 선량분포에 대해 알아보았으며 1분 치료 시 치료실 내에는 약 0.1 mSv에서 2 pSv 정도의 영향이 있을 것으로 파악되었다. The purpose of this study was to comparison of measure signal to noise ratio (SNR) according to change of kernel size from region of interest (ROI) of heart shadow in chest image. We examined images of chest image of 100 patients in a University-affiliated hospital, Seoul, Korea. Chest images of each patient were calculated by using ImageJ. We have analysis socio-demographical variables, SNR according to images, 95% confidence according to SNR of difference in a mean of SNR. Differences of SNR among change of equalization were tested by SPSS Statistics21 ANOVA test for there was statistical significance 95%(p<0.05). In SNR results, with the quality of distributions in the order of kernel size 9*9 image, kernel size 7*7 image and original chest image, kernel size 3*3 image (p<0.001). In conclusion, this study would be that quantitative evaluation of heart shadow on chest image can be used as an adjunct to the kernel size chest image.
몬테카를로 시뮬레이션을 이용한 중입자 치료실의 선량분포 추정
송용근(Yongkeun Song),허승욱(Seunguk Heo),조규석(Gyuseok Cho),최상현(Sanghyun Choi),한무재(Moojae Han),박지군(Jikoon Park) 한국방사선학회 2017 한국방사선학회 논문지 Vol.11 No.6
꿈의 암치료기라고 불리는 중입자 치료는 환자의 암세포에 입사하여 암세포만을 사멸하고 사라지는데 이때 중성자 및 감마선이 발생되어 치료실 내 영상장비, 그 밖의 전자장비에 영향을 미치게 된다. 중입자 치료시설을 구축하기 위해서는 약 2,000억 원 가량의 예산이 필요하며 구축기간도 5년 이상 소요된다. 따라서 구축 전 몬테카를로 시뮬레이션을 이용하여 치료실 내 선량 분포에 대해 관찰하여 적절한 대비를 하는 것이 중요하다. 본 연구에서는 몬테카를로 시뮬레이션 툴인 FLUKA를 이용하여 중입자 치료 시 치료실내 선량분포에 대해 알아보았으며 1분 치료 시 치료실 내에는 약 0.1 mSv에서 2 pSv 정도의 영향이 있을 것으로 파악되었다. Heavy ion therapy has a high cure rate for cancer cell. So many countries are introducing heavy ion therapy facility. When treating a cancer using heavy ion therapy, neutrons and gamma rays are generated and affect electronic equipment. A budget of about KRW 200 billion is needed to build a heavy ion therapy facility, and it takes more than five years to build it. Therefore it is important to observe the dose distribution in the treatment room using the monte carlo simulation before construction. In this study, we used the FLUKA of monte carlo simulation to investigate the dose distribution in the heavy ion treatment room.
So Young CHOI,Jeonghun OH,JaeHwang JUNG,YongKeun PARK,Sang Yup LEE 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
As plastic pollution has been emerging as a serious environmental problem, polyhydroxyalkanoates (PHAs) have been attracting much attention. PHAs are biodegradable natural polymers accumulated in the form of insoluble granules within numerous microorganisms and can be used for various applications such as disposable products, packaging, and medical uses. Despite great advances in PHA research, spatiotemporal characteristics of PHA granule formation in a live bacterial cell are not well understood due to technical limitations. Here, we observed and quantitatively analyzed how PHA granule is being accumulated in living bacteria cells through 3D holographic microscopy. A deeper understanding of PHA granule formation in vivo is now possible, which will help develop efficient microbial plastic factories.